A baby’s cranium is constantly changing. The bones are soft, the sutures are open, and the base of the skull is still shaping. At this stage, the Eustachian tube—which drains fluid from the middle ear—is shorter, more horizontal, and easily affected by pressure from nearby bones and soft tissues. Even small twists or tightness around the temporal bone, jaw, or base of the skull can change how well the tube drains. When fluid doesn’t drain properly, it collects behind the eard